1. Field of the Invention
The present invention generally relates to a stereoscopic display device, and more particularly to a stereoscopic display device and a display method thereof.
2. Description of Prior Art
Please refer to FIG. 1, which illustrates a liquid crystal lens (LC lens). The liquid crystal lens comprises two glass substrates 100, 102, two indium tin oxide layers (ITO layers) 104, 106, two alignment layers 108, 110 and a liquid crystal layer 112. In the liquid crystal lens, a voltage is applied to the two indium tin oxide layers 104, 106, such that liquid crystals 114 of the liquid crystal layer 112 has characteristics of refractive index changes, such as a gradient refractive index lens (GRIN lens).
Please refer to FIG. 2A and FIG. 2B, which respectively illustrate that no driving voltage is applied to the liquid crystal lens and a driving voltage is applied to the liquid crystal lens. As shown in FIG. 2A, when no driving voltage is applied to the two indium tin oxide layers 104, 106, a long axis of the liquid crystals is oriented by the alignment layers 108, 110. When light waves 116 pass through the liquid crystals 114, a phase thereof is not changed. When the driving voltage 118 is applied to the indium tin oxide layers 104, 106, different electric field distributions are formed due to different potentials between the indium tin oxide layers 104, 106. Fringing field effect in edges of the indium tin oxide layers 104, 106 causes the electric fields to have gradient changes. The liquid crystals 114 are affected by the electric fields, and finally the long axis of the liquid crystals 114 is oriented by the electric fields. When the light waves 116 pass through the liquid crystals 114, the phase thereof is changed with the refractive index changes of the liquid crystals 114 and the light waves 116 are focused. Since the change of the phase of the light waves 116 is similar to a lens, the structure in FIG. 2B is called as the liquid crystal lens.
The above-mentioned liquid crystal lens together with a display panel (not shown) may be served as a two-dimensional/three-dimensional (2D/3D) image switching display device. When no driving voltage is applied as shown in FIG. 2A, light waves which are emitted by the display panel (not shown) are not affected by the liquid crystals 114 and the phase thereof is not changed. Accordingly, a two-dimensional image can be displayed. When a driving voltage 118 is applied as shown in FIG. 2B, the light waves which are emitted by the display panel (not shown) are affected by the liquid crystals 114 and the phase thereof is changed. Since the liquid crystals 114 have optical characteristics similar to the lens, human eyes of a viewer can observe different images after the light waves are split. As a result, an object of displaying a three-dimensional image can be achieved.
A conventional three-dimensional display device is designed for being utilized in a full-screen mode. However, a user interfaces which is displayed by a popular operating system is still a two-dimensional image. When a movie which is observed by the observer is not in the full-screen mode and a three-dimensional mode is started, the user interface (two-dimensional image) is blurred because the user interface (two-dimensional image) is in the three-dimensional mode. Although the problem that the user interface is blurred may be solved by utilizing the above-mentioned liquid crystal lens and switching the liquid crystal lens to be in a two-dimensional mode, system multiplexing operations cannot be performed. That is, the operation of displaying the two-dimensional image in the two-dimensional mode and the operation of displaying the three-dimensional image in the three-dimensional mode cannot be performed simultaneously.
Consequently, there is a need to solve the problem that the two-dimensional image and the three-dimensional image cannot be displayed simultaneously.